The present invention relates to a metal-sawing machine, and more particularly, to a metal-sawing machine including a saw-blade rocking system whereby the saw blade is enabled to rock in a plane along which the work is cut, wherein the rocking motion of the saw blade is controlled so as to conform to the cutting stroke without excess or deficiency, irrespective of the cross-sectional shape and size of the work. The saw blade is enabled to pass through the work by following a most desired arch-like cutting trace.
The inventor has made improvements on the known metal-sawing machines, particularly about the rocking system. In the new type of metal-sawing machine the saw carrier is constructed so as to enable the saw blade to rock in a plane along which the saw blade is passed through the work, thereby ensuring that the path of the saw blade through the work is made arch-like. The arch-like cutting trace is known to be most desired for the metal sawing, because the cutting drag exerting on the saw blade is considerably reduced owing to the reduced contact of the blade with the work. In addition, the saw blade is effectively prevented from slipping off on the work, which leads to a shortened cutting time.
In the prior invention, however, the rocking range is fixed irrespective of the shape and size of the work, whereas the cutting strokes are varied particularly when the work has a circular cross-section, where the cutting stroke gradually becomes large toward the middle portion of the work and becomes small toward the terminating end. As a result most of the arch-like cutting trace followed by the saw blade is ineffective, in that the saw blade cuts only "air". It is when the cutting stroke conforms to or falls within the rocking range that the work efficiently is cut by the saw blade following arch-like traces, where no waste occurs in the movement of the saw blade.
Another disadvantage of the prior rocking system is attributed to the structure in which the saw blade is descended at a gradual constant speed against the work while it is in a rocking motion. This causes uneven cutting amounts at each rocking stage. The varied cutting amounts mean varied resistances between the saw blade and the work. To overcome the varied resistance so as to enable the saw blade to drive into the work equally, an excessive amount of force is likely to impart to the saw blade, which shortens the life of the blade.